Post or bollard type barriers are employed to control access to entranceways, driveways, roads and the like, and to also secure the perimeter around buildings, structures, and other objects. Typically, post or bollard type barriers control access by extending above grade a distance necessary to prevent traffic flow, such as vehicles, from traveling beyond the barrier.
Depending on the situation, a post or bollard type barrier may be either stationary thereby maintaining a constant above grade position, or retractable, wherein the post or bollard can be interchangeably positioned from an above grade extended position to a below grade retracted position whereby the bollard can be locked in position to allow vehicles or other objects access beyond the barrier.
In instances where a vehicle or other object impacts a bollard that is extended above grade, energy from the impact may travel along the length of the bollard toward the surrounding ground or support structure resulting in structural damage to either or both the barrier and the ground or support structure. Often, the damage results in the bollard and the surrounding ground or support structure being repaired and/or replaced. Post impact repairs to the bollard and surrounding ground or support structure can be time consuming and costly.
In other instances, vibration associated with the passage of vehicles over or near a retracted bollard may cause the retracted bollard to unintentionally unlock and extend out from a locked position below grade to an extended position above grade—potentially resulting in unwanted collisions between the bollard and a vehicle or other object.
A bollard type barrier is desired that decreases or otherwise eliminates damage to the surrounding ground or support structure following impact while also protecting against unintentionally unlocking or potential extension of the barrier above grade.